About this calculator
The Percent Decrease Calculator finds how much a value has fallen or calculates the new value after a percentage decrease. It is useful for discounts, price drops, reduced marks, lower costs, stock changes, and comparing old and new measurements.
percent decrease calculator formula
To find percentage decrease, compare the fall with the original value. To apply a decrease, multiply by one minus the percentage as a decimal.
- percent decrease = ((original value - new value) / original value) x 100
- new value = original value x (1 - percent / 100)
How to use the percent decrease calculator
- Choose whether to find the percentage decrease or the new value.
- Enter the original value.
- Enter the new value or decrease percentage.
- For percentage decrease, subtract new from original.
- Divide by the original value and multiply by 100.
- For new value, multiply by 1 minus the decimal percentage.
Worked examples
Find the decrease
Input: 100 to 80
Calculation: ((100 - 80) / 100) x 100
Result: 20% decrease
Apply a discount
Input: Original 60, decrease 25%
Calculation: 60 x 0.75
Result: 45
Discounts
A percentage decrease is often used for discounts. A 20% discount means you pay 80% of the original price.
Decrease followed by increase
A 20% decrease followed by a 20% increase does not return to the original value because the second percentage uses a lower base.
Percentage calculation note
This calculator is for education, checking, and general planning. Percentage results depend on the inputs and the chosen method, so check whether your question asks for percent change, percent difference, percent error, reverse percentage, or a simple conversion.
- Percent change has direction, but percent difference does not.
- Reverse percentage calculations can be confused with percentage increase or decrease.
- Rounded percentages may not reverse exactly to the original values.
Frequently asked questions
Does this show the working?
Yes. The percentage calculators show the key formula and calculation steps.
What does percent mean?
Percent means per hundred, so 25% means 25 out of 100.
Why do some percentage answers differ?
Different percentage questions use different reference values. Percent change, percent difference, and percent error are not the same.
Can percentages be more than 100?
Yes. A percentage can be above 100 when a value is larger than the reference whole.
Should I round the answer?
Round only to the precision required by your homework, report, invoice, or calculation context.
Related calculators
- Percent Change Calculator
- Percent Increase Calculator
- Percent to Total Calculator